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The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerves because part of it was formerly believed to originate in the brain.
There are several options of treatment when iatrogenic (i.e., caused by the surgeon) spinal accessory nerve damage is noted during surgery. For example, during a functional neck dissection that injures the spinal accessory nerve, injury prompts the surgeon to cautiously preserve branches of C2, C3, and C4 spinal nerves that provide supplemental innervation to the trapezius muscle. [3]
The spinal root of accessory nerve (or part) is firm in texture, and its fibers arise from the motor cells in the lateral part of the anterior column of the gray substance of the medulla spinalis as low as the fifth cervical nerve.
The cranial root of accessory nerve (or part) is the smaller of the two portions of the accessory nerve.It is generally considered as a part of the vagus nerve and not part of the accessory nerve proper because the cranial component rapidly joins the vagus nerve and serves the same function as other vagal nerve fibers. [1]
Accessory nerve disorder; J. Jugular foramen syndrome; S. Spinal accessory nucleus; Spinal root of accessory nerve This page was last edited on 15 November 2017, at ...
From here, the accessory nerve courses through the posterior triangle of the neck to enter the anterior border of the trapezius muscle at a point located approximately at the junction of the middle and lower thirds of the anterior border of this muscle. The spinal accessory nerve can often be found 1 cm above Erb's point. [4]
The nucleus ambiguus is classically said to provide the "cranial component" of the accessory nerve. However, the very existence of this cranial component has been recently questioned and seen as contributing exclusively to the vagus nerve. The terminology continues to be used in describing both human anatomy, [1] and that of other animals. [2]
In human anatomy, the accessory obturator nerve is an accessory nerve in the lumbar region present in about 29% of cases. It is of small size, and arises from the ventral divisions of the third and fourth lumbar nerves. Recent evidence support that this nerve arises from dorsal divisions.